Arc oscillation-generator.



- B. LIEBOWITZ.

ARC OSCILLAHON GENERATOR.

m ucmou men mmzs. m5.

Patented July 2, 1918.

331 A [5 Gimme BENJAMIN LIEBOWITZ, OF NEW YORK, N; Y.

ARC OSCILLATION-GENERATOR.

Application filed January 28, 1915.

a To all whom it may concern Oscillation-Generators, of which the following is a specification.

My invention relates to the art of generating high frequency electrical oscillations, such as are used, for example, in radio-telegraphy and telephony. The object of my invention is to provide a simple and inexpensive generator for producing electrical oscillations.

One form of my invention consists of a vapor electric device having two cathodes and an anode. Each cathode is connected to the negative terminal of a high-voltage source of direct current through a large inductanceand a resistance; and the anode, likewise through an inductance, to the positive terminal. An oscillatory circuit is shunted between the cathodes.

The above will be more readily understood by reference to the drawings in which Figure 1 is a diagrammatic view of my invention used in connection with a mercury vapor tube, the tube being partly in section, and Fig. 2 is a diagrammatic view of a modification which enables alternating current source to be used, a single tube being employed for rectifying and for generating the oscillations.

Referring to Fig. 1, a source of high voltage direct current such as a high voltage dynamo, is shown at 1, with plus and minus terminals as indicated. To prevent high frequency energy from getting back into the supply circuits, I provide an inductance shown at 2, although any other suit able means may be employed for this purpose. 3 designates a mercury vaportube having an anode 4, and two mercury cathodes, 5 and 6. Cathode 5 is connected to the negative terminal of 1 through a large inductance 7 and a resistancet), and cathode 6 is likewise connected through the inductance 8 and resistance 10. Since these cathodes alternately carry the main current through the tube, they may be called arc ing cathodes. Inductance 7 and resistance 9. may be conveniently combined into a smgle coil having proper inductance and re- Specification of Letters Patent.

Patented July 2,1918. Serial No. 4,965.

as to have minimum distributed capacity.

An oscillatory circuit, comprising, for example, a condenser 11 and inductance 12, is connected between the cathodes as shown.

.The tube may be started in a variety of ways, well 'known in the art. The method shown here is as follows: A switch 13 in the oscillatory circuit is opened, and a double throw switch 14 is thrown to the left. These positions are shown by the dotted lines in the figure. The cathode 6 is thus temporarily made a starting anode, and by tilting the tube in the usual manner, the discharge through cathode 5 is started and will be maintained. Switch 1-l is now thrown to the right, the position shown in the drawing by the full lines, and if the tube is again tilted, cathode 6 will be started. Two such parallel discharges are ordinarily highly unstable, but if each cathode is supplied through a suitable inductance, as

shown, the parallel discharges'arerendered stable and will run indefinitely under suitable conditions.

The stability produced by the inductance in series with each cathode is destroyed if .a condenser is shunted across the cathodes,

and it is owing to this fact that the system can be made to oscillate. One mode of operation is as follows:

Suppose that the parallel discharges are operatlng steadily, the switch 13 being open.

Let this switch now be closed, (position.

. In a very short time the condenser attains a voltage, say V, sufiicient to start a discharge in the tube between 5 and 6, hence the oscillatory circuit begins to execute an oscillatory discharge around the path 11, 12, 13, 6, 5, 11. Discharging under ordinary circumstances the condenser would attain at the end 'of the first half-swing a voltage (V-'o) which is reversed in sign to the original voltage V and smaller in value than V. But as soon as the condenser circuit begins to discharge through the tube, cathode 5 is started again and cathode 6 extinguished. The current through inductance 8 must now pass through cathode 5, hence while the oscillatory circuit is executing its shortly before or after the end, of the first half-swing, therefore, the condenser voltage wil1' not be (Vv) but V, which voltage is suflicient to'start the reverse discharge between 5 and 6. The condenser circuit now begins to execute its second half-swing, starting cathode 6 and extinguishing cathode 5 again. The condenser voltage tends toward the maximum value (V-v), but the inductance 7 must now discharge into the condenser, so that the voltage V is reached again, and the process repeats itself.

When the system is operating in the manner described the oscillations produced are undamped and practically sinusoidal. The system may oscillate in other ways, however, giving for example rapid series of slightly damped waves, or other types of waves. The manner in which the system oscillates is determined by the magnitude and charac ter of the various constants which enter into the circuits.

In the drawing the cathodes 5 and 6 are shown constricted where the discharge enters them. I prefer to make the cathodes in this form because better results have been obtained with them than with mercury pools of the ordinary type.

It is found by experiment that in order to obtain steady oscillations the ratio of in ductance to capacity in the oscillatory circuit must be very large. The oscillatory circuit can be connected or coupled to the' antenna or other circuits in any desired manner; and, under proper conditions, the antenna itself may be the oscillatory circuit or part thereof.

My invention may be adapted for use with alternating current supply. Single phase may be employed, but I prefer to use polyphase. Referring to Fig. 2, which shows my invention adapted for use on a two-phase system, 20A and 20B indicate the twophase supply, 2l'and 23 are the primaries of a pair of transformers, 22 and 24 are the secondaries of the same. The primaries are supplied through the series reactances 25 and 26. The tube 3 is provided with four anodes, 4 4 4, and 4. Special care is necessary to prevent arcing between these anodes. The terminals of 22 are connected to anodes 4 and 4", those of 24 to 4 and 4. The mid-points of the secondaries 22 and 24 are connected together, and from these midpoints run the parallel paths 7, 5 and 8, 6. The significance of these and the remaining members is the same as. in Fig. 1. In order not to complicate the figure, starting means are not shown. as shown in and described in connection with F ig. 1, or in a variety of other ways. It is understood. of course. that means are tion.

The tube may be started" provided for preventing high frequency energy from getting back into the supply circuits.

Such means may be incorporated in the transformers themselves, for example.

It Will be observed that the extra resistances 9 and 10 of Fig. l are not shown in Fig. 2, and that series reactances 25 and 26 are shown in Fig. '2, through which the primaries are supplied. The reason for this is as follows: In Fig. l the extra resistances are necessary in order to limit the starting cur rent, that is, the current drawn by the circuits after the parallel discharges are started and before the oscillations have been set so up. In Fig. 2, however, where alternating current is employed, the starting current is limited by the series reactances 25 and 26, hence only small series resistances are necessary; hence the form shown in Fig. 2 is more eiiicient than that in Fig. 1. If the transformers of Fig. 2 are constructed to have suiiicient leakage, then the series reactances are unnecessary. All that is necessary is a loose coupling between the primaries and secondaries of the supply circuits.

The form of my invention shown in Fig. 2, is designed to work on an alternating current supply, and accordingly performs the function of rectification as well as genera- The rectifying action which takes place is well understood in the art. The use herein described of an alternating current supply loosely coupled to rectifying circuits and an arc oscillation generator gives improved efficiency in any are oscillation generator.

I have shown my invention used in connection with mercury arcs in vacuo, but my invention is not to be construed as limited to these arcs, as the double cathode method herein described may be employed in connection with any of the arcs which may be used forgenerating oscillations, whether vapor arcs in cacao or otherwise, of the type in which the source of instability lies at the cathodes and not in the positive column. It should be noted that my invention differs from the previous devices employing double discharges in that in my device the discharge of the cathode is through a common positive column to a common anode, whereas in the previous devices the two discharges are independent throughout their entire lengths. This distinction is exceedingly important. for it has been demonstrated experimentally that when two ordinary carbon arcs are merged so as to discharge to a common positive crater the instability arising upon shunting a condenser across the cathodes is greatly reduced as compared with the insta bility when the two arcs are not merged. This is due to the fact that in the ordinary carbon arcs the source of instability is in the positivecolumn. In the mercury vapor arc, on the other hand, as my experiments have demonstrated, the instability lies at the cathode. When it is desired to rectify and generate in a single are, however, vapor arcs in oacuo must be employed, as shown in Fig. 2.

I have described certain specific forms of my invention, but the invention is not to be positive column, means for stabilizing parallel discharges from said cathodes, and an oscillatory circuit connected between said cathodes.

2. In an oscillation generator, the combination with a source of supply and a system of supply circuits, of a vapor electric device, a pair of arcing vaporizable cathodes in said vapor electric device discharging through a common ositive column, means for stabilizing paral el discharges from said cathodes, and an oscillatory circuit connected between said cathodes.

3. In an arc oscillation generator, the combination with a source of supply and. an anode, of a pair of arcing cathodes discharging througha common positivecolumn to the anode, an inductance and resistance in series with each of said cathodes, and an oscillatory circuit connected between said cathodes.

4. In an arc oscillation generator, the combination with a source of supply and an anode, of a pair of'arcing cathodes discharging through a common positive column to the anode, an inductance in series with each of said cathodes, and an oscillatory circuit connected between said cathodes.

5. In an arc oscillation generator, the combination with a source of supply and an anode in series with an inductance, of a pair of arcing cathodes discharging through a common positive column to the anode, an inductance and resistance in series with each of said cathodes, and an oscillatory circuit connected between said cathodes.

6. In an arc oscillation generator, the combination with a source of supply and an anode in series with an inductance, of a pair of arcing cathodes discharging through a common positive column to the anode, an inductance in series with each of said cathodes, and an oscillatory circuit connected between said cathodes.

7. In a oscillation generator, the combination with a source of supply and a vapor electric device, of a pair of arcing cathodes dischargin through a common positive column in said vapor electric device, an inductance and resistance in series with each of said cathodes and an oscillatory circuit connected between said cathodes.

8. Inv an oscillation generator, the combination with a source of supply and a vapor electric device, of a pair of arcing cathodes discharging through a common positive column in said vapor electric device, an inductance in series with each of said cathodes and an oscillatory circuit connected between said cathodes.

9. In a vaporarc oscillation generator, the combination with a source of supply and an anode, of a pair of arcing vaporizable cathodes discharging in common to said anode, an inductance and resistance in series with each of said cathodes, and an oscillatory cir-,

cuit connected between said cathodes.

10. In a vapor arc oscillation generator, the combination with a source of supply and an anode, of a pair of arcing vaporizable cathodes discharging in common to said anode, an inductance in series with each of said cathodes,,and an oscillatory circuit connected between said cathodes.

11. In a vapor arc oscillation generator,

the combination with a source of supply andan anode in series with an inductance, of a pair of arcing vaporizable cathodes discharging in common to said anode, an inductance and resistance in series with each of said cathodes. and an oscillatory circuit connected between said cathodes.

12. In a vapor arc oscillation generator, the combination with a source of supply and an anode in series with an inductance, of a pair of arcing vaporizable cathodes dischargingin common to said anode, an inductance in series with each of said cathodes, and an oscillatory circuit connected between said cathodes.

13. In an oscillation generator, the combination of an exhausted vessel, a pair of vaporizable cathodes and an anode in said exhausted vessel, said cathodes discharging through a common positive column to said anode, an inductance in series with said anode, a high voltage source of direct current, an inductance and resistance in series with each of said cathodes, through which inductance and resistance each of said cathodes Y is connected tothe negative terminal of said source of direct current, said anode being connected to the positive terminal of said source of direct current, and an oscillatory circuit connected between said cathodes.

14. In an oscillation generator, the combination with a source of supply and a vapor electric device, of a pair of constricted arcing cathodes in said vapor electric device, an inductance and resistance in series with each of said cathodes, and an oscillatory circuit connected between said cathodes.

15. In an oscillation generator, the combination of a source of supply and a vapor electric device, of a pair of constricted arcing cathodes in said vapor electric device, an inductance in series with each of said cathodes, and an oscillatory circuit connected between said cathodes.

16. In an oscillation generator, the combination with a source of supply and a vapor electric device, of a pair of arcing cathodes in said vapor electric device, an inductance and resistance in series with each of said cathodes, and an oscillatory circuit having a large ratio of inductance to capacity connected between said cathodes.

17. In an oscillation generator, the combination with a source 0t supply and a vapor in said vapor electric device, an inductance in series with each of said cathodes, and an.

oscillatory circuit having large ratio of inductance to capacity connected between said cathodes. I

Dated, New York, Jan. 18, 1915.

In testimony whereof, I have hereunto aflixed my signature in the presence of two subscribing witnesses.

BENJAMIN LIEBOWITZ.-

Witnesses:

Les'rnn F. DITTENIIOEFER, GRACE M. RIVIERE. 

